As the foregoing display device, proposed is a display device which displays a color video picture configured from the three primary colors of red, green and blue with four colors on a display portion having pixels including red sub pixels, green sub pixels, blue sub pixels and white sub pixels (for example, refer to Patent Document 1). In the device described in Patent Document 1, a minimum value among the three-primary-color signals is generated as a white output control signal, and this white output control signal and three-primary-color output control signals obtained by subtracting the white output control signal from the foregoing three-primary-color input video signals are supplied to the display portion.
However, in the device described in Patent Document 1, since the white sub pixels are always used for a color that can be reproduced using the red sub pixels, the green sub pixels and the blue sub pixels or for a color that can be reproduced using the white sub pixels, the red sub pixels, the green sub pixels and the blue sub pixels become dark in comparison to the white sub pixels, and there were cases where black vertical streaks would become noticeable.
Patent Document 1: Japanese Patent Application Publication No. 2004-286814